Fabrication plants that manufacture semiconductor electronic components from semiconductor wafers typically include a wide variety of process stations at which wafers in different stages of manufacturing undergo process steps, are evaluated for the possible presence of defects, or are catalogued, sorted, or otherwise handled. To reduce the risk of contamination and breakage brought about by activity of human beings, the process stations typically are partly or wholly automated.
The wafers are typically moved from one station to another in a wafer carrier that a human being manually installs in and later removes from a process station. The wafer carrier is typically designed to allow automated removal of wafers from it and insertion of wafers into it and to allow contaminants present on or around wafers in it to drop away from it. A handle is usually placed at the top of the carrier so that a human being can conveniently hold it with one hand while walking between process stations.
Because of the high throughput of contemporary fabrication plants, employees who load wafer carriers into, remove them from, and move them among process stations may handle loaded carriers hundreds of times each day. Those employees have loaded the carriers into, or removed them from, process stations by holding the top handle in one hand and flexing the wrist to which that hand is connected to load the carrier into, or to remove it from, an operating position in which the carrier is oriented for presentation of the wafers to the apparatus. A fully loaded wafer carrier may weigh as much as 4 kilograms (about 9 pounds). The weight of the carrier when it holds a substantial fraction of its capacity of wafers places substantial stress on the flexed wrist; that stress is believed to be a substantial cause of an unusually high rate of so-called "repetitive strain injuries" or "cumulative trauma" such as carpal tunnel injury, a painful and potentially disabling condition, among those workers. There is a need to reduce the incidence of such injuries.